This invention relates to a method and apparatus for the testing of the adhesion between the polyethylene coating and the paperboard stock of polyethylene coated paperboard stock of type typically used for the manufacture of milk and fruit juice cartons. In the manufacture of such cartons, it is often desirable to test the quality of adhesion between the extruded polyethylene coating on the paperboard and the paperboard. Prior to this invention, the industry has lacked a satisfactory test for evaluating this adhesion. Prior practice required searching for weak adhesion areas with a very unreliable and and subjective knife technique.